Scientists finally have a rough picture of the ancient fault that’s been rattling the Dallas area, and the fissure isn’t where the public thought it was.

Armed with more equipment and better data, SMU scientists have relocated dozens of quakes on the federal government’s imprecise maps. The team released a new map on Friday that shifts the epicenters of nearly all of last month’s temblors, arranging them in a neat line that shadows a fissure miles beneath the earth.

And while the team has just begun to study that fault, they already have some early hints about its nature.

It’s not beneath the old Texas Stadium site, as federal maps suggested.

It’s small (for a fault) and appears to be quieting down after tossing off about four dozen quakes in a year. But it could still produce a tremor much more powerful than any Dallas has yet seen.

And while scientists are skeptical that gas drilling woke it up, they now know the fault runs much closer than previously thought to the only two fracking wells in the area.

Map of epicenters

If you’ve felt any of the earthquakes to hit the Dallas area since last fall, you may have looked up a map of their epicenters. The rough bull’s eye of quakes around the old Texas Stadium site has sparked wild theories about the stadium’s demolition and jokes about the “Jerry Jones Fault.”

That map is wrong, and scientists have always known it.

The federal government estimated the North Texas epicenters using a small handful of quake detectors, some of which sat miles away and produced inaccurate readings.

The U.S. Geological Survey’s blob of approximate quake locations was of little use to scientists trying to map the underground crack producing them. So in early January, the SMU team began to install nearly two dozen detectors in the Irving area to collect more accurate data.

The earth obliged with more than two dozen quakes since then, including the most powerful yet in Dallas County.

Better data yielded better maps, and SMU’s preliminary report shows a distinct line of quakes that runs from a Northwest Dallas soccer park, across the Trinity River into Irving, and ends just north of the stadium — down the road from an abandoned fracking well pad.

“That line indicates the approximate location of a subsurface fault,” reads a statement SMU sent out with the report. And now that the team has located the fissure, they can begin to study how and why it’s moving.

Seismologists can already see that the quakes seem to travel northeast along the fault as the weeks pass. And like clusters near other cities in North Texas, they seem to be fading out after last month’s furious burst. The earth under Irving continues to jostle and stir at very low levels, but the Jan. 23 quake was the last one strong enough to be felt by humans.

“This is the first step in assessing the earthquake sequence and hazard associated with it,” SMU researcher Heather DeShon said at a Friday press conference.

Scientists’ skepticism

Many residents think they already know what’s causing the quakes. The public began to blame oil and gas drilling even before new data placed most temblors within half a mile of Irving’s only fracking wells.

But scientists are skeptical.

While the SMU team has linked earlier quake clusters near Cleburne and the Dallas/Fort Worth International Airport to fracking-related activities, they noted that the Irving-Dallas fault appears to run about three to five miles underground — far deeper than Trinity East Energy drilled its wells in the late 2000s.

However, even the new quake locations might be off by thousands of feet. And the scientists are particularly uncertain about how deep they are.

“I do expect the depth to wiggle around by as much as a mile,” said DeShon. She couldn’t say whether more accurate readings might relocate some quakes into the drilling zone.

Trinity East president Stephen Fort dismissed any notion that his drilling operation could cause quakes years after it shut down.

Fort said his company knew it was drilling near a large network of faults that runs under Dallas, roughly parallel to the newly active fault under Irving.

“You try to avoid the faults,” Fort said. “And we did.”

He would not comment on a mechanical failure in one of the wells that forced the company to seal it several years ago. Nor would he say whether that well was sealed with fracking fluid inside, which might put pressure on underground rocks.

Far from the politics of Texas gas drilling, in England, Newcastle University geologist Richard Davies read the SMU report and tried to think of a way that two long-dormant gas wells could cause quakes.

“It’s not totally impossible, but I find it hard to believe,” he said.

Davies has studied some of the few fracking-induced earthquakes on record. But he noted that those tremors took place no more than a few hours after drillers pumped chemically-laced water into the rock, knocking oil or gas loose while possibly causing faults to slip.

The Irving wells were last fracked in 2010. Davies didn’t know of any case in which quakes occurred so long after fracking ended.

The geologist saw a more plausible connection to a wastewater injection well about eight miles from the quakes, near Dallas/Fort Worth International Airport. After drillers frack a well, they suck their slurry back out and shoot it into an essentially bottomless pit, where it can travel for unknown distances between slabs or rock.

Far more injections wells have been linked to quakes than has fracking itself. Davies suggested the SMU scientists study the airport well in case it somehow rustled Irving’s fault.

He also suggested that the cause of the Dallas-area quakes might not be so close to home.

Nearly 150 quakes have shaken North Texas since the first in 2008, and even more in Oklahoma. Davies said it’s possible for a quake to trigger a chain reaction, destabilizing a separate fault, miles away. That might be even more likely if fluid injection “primed” the second fault—lubricating a fissure that’s been under pressure for millions of years.

His thinking wasn’t far from that of the SMU scientists, who raised a similar theory on Friday.

“Sometimes what triggers an earthquake can be very small,” DeShon said in a statement accompanying the report.

Rawlings’ response

While the scientists prepared to dig into their new data, Irving and Dallas officials fanned out to put a public face on it.

Coincidentally, top Irving officials were in Austin when the report came out. They were asking the governor’s office for help in finding a cause for the quakes.

Friday afternoon, an Irving press release made sure to note that SMU’s new maps moved most of the quakes across the city line, to Dallas.

“There is not the information that ultimately I think we need, which is really about predictability and what does this mean for the future,” Dallas Mayor Mike Rawlings said at a press conference about the report. “I liken this a little bit to the Ebola situation: that we have to look at science and understand what it says about why these things happen.”